In the last twenty years, a new type of kayak has been developed and has gained increasing acceptance. This new type of kayak is referred to herein as a sit-on-top kayak. As this name suggests, the user of a sit-on-top kayak sits in an open cockpit on top of the kayak hull. The sit-on-top kayak is somewhat similar to a surfboard in overall shape, but normally has a generally v-shaped hull portion and a deeper draft to allow better tracking. Modern sit-on-top kayaks are conventionally formed out of polyethylene using a rotational molding process.
An exemplary sit-on-top kayak is depicted at 20 in FIG. 11. This kayak 20 comprises a hollow, airtight hull 22 that will not sink when the craft is flipped over. To take advantage of the unused space within the hull 22, one or more hatch openings 24 are often formed in the kayak hull 22. Gear may be stored inside the hull 22 through the hatch opening 24. To keep the hull 22 buoyant and to keep water away from the gear stored therein, a hatch cover 26 is employed to cover the hatch opening 24.
Referring now to FIG. 2, it can be seen that, to allow hatch cover 26 to cover the hatch opening 24 in a watertight manner, a hatch flange member indicated by reference character 28 is attached around the hatch opening 24. The hatch flange member 28 comprises a plate portion 30, an intermediate portion 32, and a flange portion 34. Rivets 36 and 38 pass through the plate portion 30 of the flange member 28 and the hull 22 to fix the flange member 28 onto the hull 22. A sealant (not shown) is also applied between the plate portion 30 and the hull 22 to ensure that the connection therebetween is watertight.
The hatch flange member 28 itself is made of polyethylene and is relatively rigid. The hatch cover 26 is made of natural or synthetic rubber and is resilient and flexible. The hatch cover 26 has a first cavity 40 formed therein to receive the flange portion 34 of the flange member 28. The interaction between the flange portion 34 and the first cavity 40 helps prevent inadvertent removal of the hatch cover 26. However, when removal of the hatch cover 26 is desired, the user need merely grasp a second cavity 42 in the hatch cover 26 and twist and pull the cover 26 off of the flange member 32.
The resiliency of the hatch cover 26 and the overlap between the hatch cover 26 and the flange member 28 combine to allow an essentially watertight seal to be formed over the hatch opening 24.
Conventionally, the hatch flange 28 as described above and shown in FIG. 2 is fabricated separately from the hull 22 and attached thereto after the opening 24 has been formed. This is because: (a) in order to form the recessed cockpit 44 it is necessary that the parting line in the mold used to form the hull 22 be horizontally aligned; and (b) the flange portion 34 would require negative draft in a mold having a horizontal parting line. It is the conventional wisdom in the art of the rotationally molding kayaks to avoid such negative draft.
However, it would be desirable to fabricate a hull having an integral flange portion because this would eliminate several steps in the process of fabricating a kayak such as the kayak 20 described above.